ReactCommon/renderer/mapbuffer: Migrate uses of NDEBUG to REACT_NATIVE_DEBUG + react_native_assert

Summary:
For better cross-platform consistency, migrate usages of NDEBUG to REACT_NATIVE_DEBUG. See flags.h for explanation.

Changelog: [Internal]

Reviewed By: PeteTheHeat

Differential Revision: D26695224

fbshipit-source-id: 3044049cb2447a733a9ecae84dcc099b26731acd

Author: JoshuaGross

ReactCommon/react/renderer/mapbuffer/tests/MapBufferTest.cpp

@@ -7,7 +7,6 @@
 
 #include <memory>
 
-#include <assert.h>
 #include <gtest/gtest.h>
 #include <react/renderer/mapbuffer/MapBuffer.h>